Rain is a liquid precipitation, in contrast to non-liquid precipitation such as snow, ice cubes and slit. Rain requires the presence of a thick layer of atmosphere to meet temperatures above the melting point of ice near and above the Earth's surface. On Earth, rain is the process of condensing water vapor in the atmosphere into a grain that is heavy enough to fall and usually arrives on land. Two processes that may occur together can push the air getting saturated before the rain, which is air cooling or adding moisture to the air. Virga is precipitation that falls to Earth but evaporates before it reaches the land; this is one way of saturation air. Precipitation is formed through a collision between water grains or ice crystals with clouds. Raindrops have a variety of sizes ranging from precise, like pancakes (large grains), to small balls (small grains).
The humidity that moves along the three-dimensional temperature and humidity difference zone called the weather front is the main method in making rain. If at that moment there is enough moisture and upward movement, the rain will fall from a convective cloud (cloud with a strong upward motion) like a cumulonimbus (thunderstorm) that can accumulate into a narrow rainbreak. In mountainous areas, heavy rainfall can occur if the upper flow of the valley rises at the top of the surface wind at altitudes that force moist air to condense and fall as rain along the side of the mountains. On the underside of the mountain breeze, desert climates can occur due to the dry air resulting from the flow of the valleys that leads to warming and drying of air masses.